Fence Calculator
Calculate posts, horizontal rails, vertical pickets, and concrete bags for wood fencing.
Fence Calculator Interactive Tool
Enter your project dimensions below. Results update instantly.
Results
15
13 bays (8-ft posts, 2-ft hole)39
3 rails per section209
At 5.5" width (+5% cut allowance)30
2 bags per post hole$522.50
At $2.50/picketFull Fence Material Equations
Sections = ⌈Length ÷ Post Spacing⌉ | Posts = Sections + 1 + Gates | Rails = Sections × Rails/Section | Pickets = ⌈(Length × 12) ÷ (Picket W + Gap)⌉Formula Variables:
- Post Spacing:Standard 8 feet (or 6 feet in high-wind regions).
- Rails:2 horizontal rails for 4-ft fences; 3 horizontal rails for 6-ft privacy fences to prevent warping.
- Concrete:2 fifty-pound bags of quick-setting concrete per post hole.
Gate openings require two dedicated hinge and latch posts that should be set 6 inches deeper than regular line posts.
Step-by-Step Worked Example
Example: 120-foot 6-foot privacy fence with 8-foot spacing and 1 gate
Building a 120-foot wood privacy fence with 3 horizontal rails, 5.5-inch dog-ear cedar pickets, and 1 gate opening.
- Calculate sections: 120 ft ÷ 8 ft = 15 sections.
- Calculate posts: 15 + 1 end post + 1 gate allowance = 17 posts (4×4 timber).
- Calculate horizontal rails: 15 sections × 3 rails = 45 rail boards (2×4×8ft).
- Calculate pickets: (120 ft × 12 in/ft) ÷ 5.5 in = 261.8 → 262 pickets (+ 10% waste = 289 pickets).
- Calculate post concrete: 17 posts × 2 bags = 34 bags of 50-lb fast-setting concrete.
Input Explanations & Measurement Guidelines
Total Fence Length
Typical: 80 to 200 ftCombined linear footage of all fence runs.
Post Spacing
Typical: 8 feetDistance between post centers (8 ft standard; 6 ft for exposed windy sites).
Fence Height
Typical: 6 feetFinished height (4 ft garden fence or 6 ft privacy fence).
Assumptions & Limitations
- Assumes level ground without severe stepped terracing.
- Includes standard 2 fast-setting concrete bags per line post hole.
Safety & Professional Notes
- Always confirm property boundaries with an official survey pin locate before augering holes. Always dial 811 before digging.
Frequently Asked Questions
Why do 6-foot fences need 3 rails?
Wood pickets shrink, swell, and cup with humidity. Two rails leave 3+ feet of unsupported wood that will twist and warp over time; a middle rail keeps boards straight.
How deep should fence posts be buried?
The universal rule of thumb is burying 1/3 of the total post length into the ground (or at least 6 inches below local winter frost depth).